Generally, a fixture for mounting a water bottle on a bicycle frame, such as a down tube, comprises a fixing member having a fixing means, the fixing member being fixed to the frame and carrying a support member made mainly from metallic wires. The fixing member is fixed to the frame through the fixing means and the water bottle detachably engages with the support member, thereby being mounted on the frame.
The water bottle is mainly cylindrical and has at the head thereof a faucet covered by a cap, which is mounted on the cylindrical frame through the fixture so that recessed gaps are produced between the water bottle and the frame, thereby creating a problem of increasing an air resistance against the bicycle's running.
In other words, during the bicycle's running, air flows from the front of the frame rearwardly along both sides thereof and then enters into the gaps to cause eddy air currents, the eddy air currents increasing the air resistance as a whole against the bicycle's running.
The air resistance will increase in proportion to the running speed of the bicycle to thereby hinder its running at high speed and inducing increased fatigue in a driver.